Novel construction of carbon nanofiber/CuCrO2 composite for selective determination of 4-nitrophenol in environmental samples and for supercapacitor application

A simple hydrothermal process has been used to prepare a carbon nanofiber/copper chromium dioxide (CNF/CuCrO2) composite for the selective detection of 4-nitrophenol (4-NP) and supercapacitor applications.

Colorimetric method as alternative to chromium (III) quantification in cattle feces

One of the main factors to establish productivity of grazing cattle is the estimation of forage intake. For this, the most widely used technique is based on the estimation of fecal output using chromium dioxide as external marker. However, quantification can be expensive and sometimes not precise due to the methodology used for this purpose. Therefore, the aim of this study was to validate the colorimetric method for chromium quantification and to implement it in the estimation of fecal output in grazing cattle. The temperature, the digestion time and the wavelength for the measurement were evaluated. The method was validated for selectivity, linearity, detection and quantification limits, precision, accuracy, and stability. Results showed that temperature and digestion time are critical to improve sensitivity and quantification limits. The validation demonstrated that the method is suitable for the quantification of Cr2O3 in a wide range of concentrations, being statistically comparable with a reference method, and offering a reliable low cost and easy to implement alternative, to estimate fecal output in bovine digestibility studies.

Hydrothermal Synthesis of CrO2 Nanoparticle Arrays on Ti nano-pit Array Templates

Chromium dioxide (CrO[Formula: see text] nanoparticle arrays were fabricated on Ti nano-pit array templates by hydrothermal synthesis using CrO3 aqueous solution as precursor. The Ti nano-pit array template was obtained by stripping TiO2 nanotube array formed on the Ti foil. CrO2 nanoparticles are arranged in honeycomb pattern in a large area and their surface density reaches [Formula: see text][Formula: see text]cm[Formula: see text]. The CrO2 nanoparticle arrays show typical magnetic behavior, and the easy axis is parallel to the plane of Ti nano-pit array template. The influence of the concentration of CrO3 aqueous solution on the CrO2 nanoparticle arrays is studied and the mechanism of the formation of the CrO2 nanoparticle arrays is briefly discussed.